Localization of phenobarbital- and 3-methylcholanthrene-inducible cytochromes P-450 in mouse lung with monoclonal antibodies

The cytochromes P-450 are key components of the mixed-function oxidase system responsible for the biotransformation of many foreign compounds to mutagens and carcinogens. In the present study, the distribution of these hemoproteins in frozen sections of mouse lung was determined immunohistochemically, using monoclonal antibodies (Mabs). Mab 1-7-1 is specific for 3-methylcholanthrene-inducible cytochromes P-450; this Mab reacted intensely with parenchymal cells, but not epithelial cells of pulmonary bronchioles of 3-methylcholanthrene-treated mice. Mab 1-7-1 did not react with pulmonary cells of either untreated or phenobarbital-treated mice. Mab specific for phenobarbital-inducible cytochromes P-450, Mab 2-66-3, reacted with parenchymal and bronchiolar epithelial cells in the lungs of phenobarbital-treated, 3-methylcholanthrene-treated, and untreated mice. The localization of constitutive and induced forms of cytochrome P-450 in different cells of the lung may provide insight into the mechanisms by which cell-specific damage and carcinogenicity are evoked by xenobiotics.

Endobronchial tuberculosis: clinical and bronchofiberscopic features

The clinical and bronchofiberscopic features of endobronchial tuberculosis in 53 patients were investigated. These patients comprised 4.7% of some 1,132 subjects who had undergone flexible bronchofiberscopic examinations. The peak incidence occurred in the third and fourth decades, a secondary peak appeared in the seventh decade, a five to six times higher incidence was noted in the female than in the male. Staining for acid-fast bacilli was positive in 67.9% of the patients sputums and or specimens of bronchial washings. A barking cough was the most common chief complaint. Next in order were chest pain, production of mucus, dyspnea, hemoptysis, and fever. Twenty-three out of 53 patients showed abnormalities on their chest films.

The flexible bronchoscope revealed tuberculous lesions characterized by mucosal swelling or edema, redness, erosion, ulceration, hypertrophy with luminal narrowing, and cicartical stenosis due to whitish pseudomembrane. The left lower and upper bronchi were involved most frequently.

The majority of the patients who were suffering from a barking cough were resistant to antitussive agents but were responsive to steroid combination chemotherapy with antituberculous drugs.

In conclusion, the bronchofiberscopic approach is not only helpful in the differentiation of endobronchial tuberculosis from bronchogenic cancer but it can also be used for relieving atelectasis.

Amino-terminal sequence and structure of monoclonal antibody immunopurified cytochromes P-450

Six hepatic cytochromes P-450 were isolated from 3-methylcholanthrene-treated animals by immunopurification with monoclonal antibodies. The purified cytochromes P-450 include 57- and 56-kDa polypeptides from Sprague-Dawley rats, 57- and 56-kDa polypeptides from C57BL/6 mice, a 56-kDa polypeptide from DBA/2 mice, and a 53-kDa polypeptide from guinea pigs. These isozymes were structurally compared by peptide mapping using both sodium dodecyl sulfate--polyacrylamide gel electrophoresis and high-pressure liquid chromatography and by amino acid and NH2-terminal sequence analyses. The 57-kDa polypeptides from rats and mice have similar but nonidentical peptide maps and amino acid compositions and are about 80% homologous in their NH2-terminal amino acid sequence. The 56-kDa polypeptides from rats and both mice strains have very similar peptide maps and amino acid compositions and identical NH2-terminal sequences. The NH2-terminal sequence of the mice 56-kDa polypeptides corresponds to that reported for the mouse P1-450 isozyme except that we identified two additional residues, proline and serine, at the NH2 terminus in the 57-kDa polypeptide from C57BL/6 mice that were not deduced from the cDNA sequence of the mouse P1-450 isozyme. The guinea pig 53-kDa polypeptide has a distinct peptide map relative to the other polypeptides studied and an NH2-terminal sequence with only partial homology to the 56- and 57-kDa polypeptides from rats and mice. This report shows the varying degree of structural relatedness among the isozymes examined and demonstrates the suitability and advantage of immunopurified cytochromes P-450 for sequencing and structural studies.

Monoclonal antibody-directed analysis of cytochrome P-450-dependent monooxygenases and mutagen activation in the livers of DBA/2 and C57BL/6 mice

Monoclonal antibodies (MAb 1-7-1 and Mab 2-66-3) specific for cytochrome P-450 (cyt. P-450) isozymes inhibited the metabolism of carcinogens, other xenobiotics, and endogenous compounds in two strains of mice. Postmitochondrial liver supernatant (S9) was prepared from untreated, 3-methylcholanthrene-treated, phenobarbital-treated, and pregnenolone 16 alpha-carbonitrile-treated C57BL/6 (B6) and DBA/2 (D2) mice. The modifying effect of two types of MAb to a 3-methylcholanthrene-induced cyt. P-450 and a phenobarbital-induced cyt. P-450 was investigated for: (a) S9-mediated mutagenicity of aflatoxin B1, benzo(a)pyrene 7,8-dihydrodiol, 2-acetylaminofluorene, and N-nitrosomorpholine in Salmonella typhimurium strains; and (b) the activity of aryl hydrocarbon hydroxylase, ethoxycoumarin O-deethylase, ethoxyresorufin O-deethylase, aminopyrine N-demethylase, and testosterone 6 beta-, 7 alpha-, and 16 beta-hydroxylases. With certain S9s, MAb-1-7-1 inhibited only those cytochrome P-450 isozymes involved predominantly in activity of aryl hydrocarbon hydroxylase, ethoxyresorufin O-deethylase, and ethoxycoumarin O-deethylase and mutagenicity of 2-acetylaminofluorene and benzo(a)pyrene 7,8-dihydrodiol; MAb 2-66-3 inhibited only those involved in aminopyrine N-demethylase and testosterone 6 beta-, 7 alpha, and 16 beta-hydroxylase activity and aflatoxin B1 mutagenicity. Both Mab 1-7-1 and MAb 2-66-3 inhibited cytochrome P-450 isozyme(s) implicated predominantly in testosterone 7 alpha-hydroxylation in S9 from pregnenolone 16 alpha-carbonitrile-treated B6 mice. MAb 1-7-1 did not inhibit N-nitrosomorpholine mutagenicity and MAb 2-66-3 increased it by 2- to 6-fold depending on the source of S9. Using these MAbs, it is thus possible to identify the contribution of the epitope-defined single or class of cyt. P-450 to specific metabolic reactions in S9 from untreated and inducer-treated mice.

Preparation of catalytically active cytochromes P-450 by antigen exchange on monoclonal antibody based immunoadsorbents

Catalytically active cytochromes P-450 have been prepared by monoclonal antibody (MAb) directed immunopurification using an antigen-exchange technique. Immunoaffinity-purified cytochromes P-450 that require denaturants for efficient desorption from the immunoaffinity matrix, although significantly lacking in catalytic activity, were found to retain epitopic structural integrity as probed by radioimmunoassay using MAbs to 3-methylcholanthrene and phenobarbital-induced rat liver cytochromes P-450. These denatured cytochromes P-450 were capable of displacing from the immunoaffinity matrices epitopically related cytochromes P-450 that retained aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase activities. Such epitope-specific exchange of denatured for native antigen on a solid-phase matrix containing a MAb may be generally applicable to preparation of proteins with the retention of activity.

Retention of membrane proteins by the endoplasmic reticulum

We have used a monoclonal antibody specific for a hydrocarbon-induced cytochrome P450 to localize, by electron microscopy, the epitope-specific cytochrome P450. The cytochrome was found in the rough and smooth endoplasmic reticulum (ER) and the nuclear envelope of hepatocytes. Significant quantities of cytochrome P450 were not found in Golgi stacks. We also could not find any evidence of Golgi-associated processing of the Asn-linked oligosaccharide chains of two well-characterized ER membrane glycoprotein enzymes (glucosidase II and hexose-6-phosphate dehydrogenase), or of the oligosaccharides attached to the bulk of the glycoproteins of the ER membrane. We conclude that these ER membrane proteins are efficiently retained during a process of highly selective export from this organelle.

Monoclonal antibody directed isolation and amino-terminal sequence analysis of phenobarbital induced rat liver cytochromes P-450

Cytochrome P-450 was isolated from liver microsomes of phenobarbital treated rats by an essentially single step immunopurification with a monoclonal antibody (MAb). The amino terminal sequence of the isolated cytochrome P-450 displayed a microheterogeneity of isozymes related to previously identified phenobarbital induced forms, indicating that each of these isozymes possess the MAb-specific epitope. This monoclonal antibody-based approach to isolation and subsequent identification of cytochrome P-450 may serve to classify different isozymes by their content of epitopes that bind to different MAbs.

Monoclonal antibodies to cytochrome P-450 immunopurify a 45-kDa protein from a human lymphoblastoid cell line

Monoclonal antibodies (MAbs) to rat liver cytochromes P-450 have previously been used for successful immunopurification of cytochromes P-450 from animal tissues. We now report application of this MAb-based immunopurification technique to the human lymphoblastoid AHH-1 cell line. Immunopurification carried out with 3 different MAbs each yielded a 45-kDa polypeptide. The purified protein contains an MAb-specific epitope present on cytochromes P-450, and may therefore be a human cytochrome P-450.

Monoclonal antibody-directed determination of cytochrome P-450 types expressed in a human lymphoblastoid cell line

Cytochrome P-450-dependent aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase activities of a cloned line of human lymphoblastoid AHH-1 cells are inhibited by a monoclonal antibody (MAb 1-7-1) prepared to a 3-methylcholanthrene-induced rat liver cytochrome P-450. The monoclonal antibody inhibition determined that a single MAb 1-7-1-sensitive type of cytochrome P-450 is responsible for all of AHH expression in both the basal and benz[a]anthracene-induced cells. Partial inhibition by the MAb 1-7-1, however, indicates that at least two forms of cytochrome P-450 catalyze 7-ethoxycoumarin O-deethylase in both the basal and the induced cells, one form of which is identical to the MAb-sensitive cytochrome P-450 responsible for all of the AHH. Thus, a single cloned cell line is capable of expressing two classes of cytochromes P-450, and the observed multiplicity of cytochrome P-450 in animal tissues does not necessarily depend on cell heterogeneity. A sensitive MAb 1-7-1-based radioimmunoassay also directly demonstrates the presence in these cells of a MAb 1-7-1-specific type of cytochrome P-450 as well as its elevation in the induced cells. These MAb-based methods thus can determine the contribution of specific MAb-defined types of cytochromes P-450 to the cellular metabolism of specific xenobiotics.

Monoclonal antibody-directed radioimmunoassay detects cytochrome P-450 in human placenta and lymphocytes

A multiplicity of cytochromes P-450 is responsible for the detoxification and activation of xenobiotics such as drugs and carcinogens. Individual differences in sensitivity to these agents may reside in the cytochrome P-450 phenotype. A monoclonal antibody-directed radioimmunoassay was developed that detects epitope-specific cytochromes P-450 in human placentas and peripheral lymphocytes. Placentas from women who smoked cigarettes contained greater amounts of cytochrome P-450 with the monoclonal antibody-specific epitope than placentas from nonsmokers. The amount of this cytochrome P-450 in human peripheral lymphocytes increased after treatment of the mitogenized lymphocytes with the cytochrome P-450 inducer benz[a]anthracene.

Expression of cytochromes P-450 in rat hepatoma cells. Analysis by monoclonal antibodies specific for cytochromes P-450 from rat liver induced by 3-methylcholanthrene or phenobarbital

We have studied the expression of aldrin eposidase (AE), 7-ethoxycoumarin-O-deethylase (ECDE), and aryl hydrocarbon (benzo[a]pyrene) hydroxylase (AHH) in nine differentiated or dedifferentiated cell lines derived from H4IIEC3 rat hepatoma cells. The nature of the cytochromes P-450 mediating AE, ECDE and AHH activities was analysed using monoclonal antibodies (MAb) made to the major 3-methylcholanthrene-induced cytochrome P-450 (MAb-MC) or phenobarbital-induced cytochrome P-450 (MAb-PB) from rat liver. The cells were treated with 5 microM dexamethasone for 30 h to increase the levels of the monoxygenase activities. (a) The six differentiated cell lines examined (Faza967, Fao, HF1-4, 2sFou, C2Rev7, and H4IIEC3/G-) contained MAb-PB-sensitive AE comprising 30-75% of the total AE activity. In most of these cell lines MAb-PB also markedly inhibited ECDE; however, the antibody had a considerably weaker effect on AHH. (b) MAb-PB-sensitive AHH, ECDE and AE activities were also observed in untreated and phenobarbital-treated cells. (c) MAb-MC inhibited AHH and ECDE in the two dedifferentiated lines HF1 and H5 by 50-80%. The antibody also inhibited AHH activities in the poorly differentiated line H4IIEC3/T and in the majority of the differentiated lines by 40-65%. MAb-MC-sensitive AHH was found in Fao cells after treatment with benz[a]anthracene but induced AHH in H4IIEC3/T, H4IIEC3/G-, and 2sFou cells 20-30-fold and in Faza967 and Fao cells 3-5-fold. Benz[a]anthracene remained without effect on AHH activity in C2Rev7 cells. The results show that the hepatoma cells examined express to various degrees phenobarbital-inducible cytochrome P-450 and/or 3-methylcholanthrene-inducible cytochrome P-450. These cell lines are versatile tools for studying the regulation of monooxygenase activities and analysing their role in the activation and inactivation of xenobiotics such as carcinogens, drugs and pesticides.

Detection and purification of cytochromes P-450 in animal tissues with monoclonal antibodies

Monoclonal antibody (MAb)-based radioimmunoassay (RIA) and immunopurification procedures were used to probe the immunochemical relatedness of cytochromes P-450 in tissues from different species. RIAs based on MAb 1-7-1 and MAb 1-31-2, both to the major 3-methylcholanthrene (MC)-induced rat liver microsomal cytochrome P-450, detected antigenically related forms of cytochrome P-450 in liver microsomes from MC-induced rats, C57BL/6 and DBA/2 mice, hamsters, and guinea pigs, and in lung and kidney microsomes of MC-induced rats. Individual cytochromes P-450 were also isolated from these microsomes by MAb-directed immunopurification. When bound to Sepharose, MAb 1-7-1 adsorbed two species of Mr 56,000 and 57,000 from liver microsomes from rats and C57BL/6 mice, while MAb 1-31-2 adsorbed only the Mr 57,000 polypeptide. These results reveal that livers from both rats and C57BL/6 mice contain a cytochrome P-450 (Mr 56,000) with the epitope for 1-7-1 and a cytochrome P-450 (Mr 57,000) with epitopes for both 1-31-2 and 1-7-1. Additional immunochemical relatedness between the cytochromes P-450 in different tissues was demonstrated by MAb-directed immunopurification of cytochromes P-450 from DBA/2 mouse liver (Mr 56,000), guinea pig liver (Mr 53,000), hamster liver (Mr 57,000), and rat lung (Mr 57,000). These results demonstrate the efficacy of MAb-based RIA and immunopurification procedures for simple and rapid detection and purification of cytochromes P-450 from a variety of tissues.

Amino-terminal sequence analysis of six cytochrome P-450 isozymes purified by monoclonal antibody directed immunopurification

Six hepatic microsomal cytochromes P-450 were isolated from 3-methylcholanthrene induced animals by immunopurification using two monoclonal antibodies. Two forms of cytochromes P-450 (MW 56K and 57K) were from Sprague-Dawley rats, two from C57BL/6 mice (56K and 57K), one form from DBA/2 mice (56K) and one form from guinea pigs (53K). NH2-terminal sequences of the first ten amino acids of these cytochromes P-450 were determined by automated Edman degradation. The 56K polypeptides from rats, C57BL/6 mice, and DBA/2 mice were shown to have identical NH2-terminal sequences. The 57K polypeptides from rats and C57BL/6 mice are homologous to each other but exhibit no homology to 56K polypeptides. The 53K polypeptide from guinea pigs has a unique NH2-terminal sequence with no apparent homology to the other five cytochromes P-450.

Monoclonal antibody phenotyping of interindividual differences in cytochrome P-450-dependent reactions of single and twin human placenta

Cytochromes P-450 are a family of enzymes responsible for metabolism of drug and xenobiotics, such as carcinogen, and certain physiological compounds, such as steroids and prostaglandins. We prepared a monoclonal antibody (MAb 1-7-1) to a polycyclic hydrocarbon-induced rat cytochrome P-450 that antigenically defines and inhibits a type of cytochrome P-450 responsible for aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin deethylase (ECD) activity in human placenta. We examined the placentas from single and twin births from mothers who smoked cigarettes and nonsmokers. The MAb 1-7-1 inhibited the smoking-induced AHH activity of essentially the entire population of placentas by 70 to 95%. Thus, up to 95% of the AHH in a population of human placentas is catalyzed by a type of cytochrome P-450 that contains an antigenic site recognized by MAb 1-7-1. A second type of cytochrome P-450, which is insensitive to MAb 1-7-1, is responsible for the ECD activity in the placentas of nonsmokers. In the placentas from smokers, both types of P-450 contribute to ECD activity. Their ratios can be determined by the amount of inhibition by MAb 1-7-1 which ranges from 0 to 70%. The placentas from both dizygotic and dichorionic monozygotic twins show extraordinarily high intrapair concordance for both the absolute amounts of AHH and ECD and their inhibition by MAb 1-7-1 compared with unrelated individuals, indicating that interindividual differences in these parameters of biological activity are not due to random variation or experimental error. Our results show that the amount of activity of antigenically unique types of cytochrome P-450 responsible for different drug and carcinogen reactions can be measured in different individuals by the amount of their inhibition by highly specific monoclonal antibodies. These findings may have general application to studies on the relationship cytochrome P-450 phenotype to population differences in drug and carcinogen biotransformation.

Monoclonal antibody-directed phenotyping of cytochrome P-450-dependent aryl hydrocarbon hydroxylase and 7-ethoxycoumarin deethylase in mammalian tissues

The distribution of cytochromes P-450 that catalyze aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase were studied with monoclonal antibody (MAb) 1-7-1 which completely inhibits these activities of a purified 3-methylcholanthrene-induced rat liver cytochrome P-450. The degree of inhibition by MAb 1-7-1 quantitatively assesses the contribution of different cytochromes P-450 in the liver, lung, and kidney microsomes from untreated, 3-methylcholanthrene- and phenobarbital (PB)-treated rats, mice, guinea pigs, and hamsters. Enzyme sensitivity to MAb 1-7-1 inhibition defines two types of cytochrome P-450 contributing to aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase. The MAb 1-7-1-sensitive cytochrome P-450 is a major contributor to aryl hydrocarbon hydroxylase in rat liver, lung, and kidney of 3-methylcholanthrene-treated rats, C57BL/6 mice, guinea pigs, and hamsters; this type is also present in lesser amounts in the extrahepatic tissues of the control and PB-treated animals, and in the lungs of the relatively "noninducible" DBA/2 mice treated with 3-methylcholanthrene. This form however makes little or no contribution to liver aryl hydrocarbon hydroxylase of control or PB-treated animals. 7-Ethoxycoumarin O-deethylase is also a function of both the MAb 1-7-1-sensitive and insensitive classes of cytochrome P-450. The ratio of the classes contributing to aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-deethylase differs in the various tissues and species and after inducer treatment. All of the 7-ethoxycoumarin O-deethylase activity in guinea pigs and hamsters is a function of cytochromes P-450 different than the MAb 1-7-1-sensitive cytochrome P-450 responsible for aryl hydrocarbon hydroxylase activity. Thus, the MAb 1-7-1 antigenically defines the type of cytochromes P-450 contributing to each reaction. Cytochromes P-450 can be viewed as paradigmatic for enzyme systems in which the nature and amount of product is regulated by multiple isoenzymic forms. Analyses using monoclonal antibodies to specific isoenzymes may thus have broad application to a variety of other complex systems which are composed of multiple isoenzymes.

Monoclonal antibodies to phenobarbital-induced rat liver cytochrome P-450

Somatic cell hybrids were made between mouse myeloma cells and spleen cells derived from BALB/c female mice immunized with purified phenobarbital-induced rat liver cytochrome P-450 (PB-P-450). Hybridomas were selected in HAT medium, and the monoclonal antibodies (MAbs) produced were screened for binding to the PB-P-450 by radioimmunoassay, for immunoprecipitation of the PB-P-450, and for inhibition of PB-P-450-catalyzed enzyme activity. In two experiments, MAbs of the IgM and IgG1 were produced that bound and, in certain cases, precipitated PB-P-450. None of these MAbs, however, inhibited the PB-P-450-dependent aryl hydrocarbon hydroxylase (AHH) activity. In two other experiments, MAbs to PB-P-450 were produced that bound, precipitated and, in several cases, strongly or completely inhibited the AHH and 7-ethoxycoumarin deethylase (ECD) activities PB-P-450. These MAbs showed no activity toward the purified 3-methylcholanthrene-induced cytochrome P-450 (MC-P-450), beta-naphthoflavone-induced cytochrome P-450 (BNF-P-450) or pregnenolone 16-alpha-carbonitrile-induced cytochrome P-450 (PCN-P-450) in respect to RIA determined binding, immunoprecipitation, or inhibition of AHH activity. One of the monoclonal antibodies, MAb 2-66-3, inhibited the AHH activity of liver microsomes from PB-treated rats by 43% but did not inhibit the AHH activity of liver microsomes from control, BNF-, or MC-treated rats. The MAb 2-66-3 also inhibited ECD in microsomes from PB-treated rats by 22%. The MAb 2-66-3 showed high cross-reactivity for binding, immuno-precipitation and inhibition of enzyme activity of PB-induced cytochrome P-450 from rabbit liver (PB-P-450LM2). Two other MAbs, 4-7-1 and 4-29-5, completely inhibited the AHH of the purified PB-P-450. MAbs to different cytochromes P-450 will be of extraordinary usefulness for a variety of studies including phenotyping of individuals, species, and tissues and for the genetic analysis of P-450s as well as for the direct assay, purification, and structure determination of various cytochromes P-450.

Monoclonal antibody-directed radioimmunoassay of specific cytochromes P-450

A rapid solid phase radioimmunoassay (RIA) for cytochromes P-450 has been developed utilizing specific monoclonal antibodies to major forms of rat liver cytochrome P-450 that are induced by 3-methylcholanthrene (MC-P-450) and phenobarbital (PB-P-450). Monoclonal antibodies (MAbs) that were endogenously labeled with [35S]methionine were used to detect MAb-specific cytochromes P-450 in liver microsomes from untreated rats and rats pretreated with 3-methylcholanthrene (MC) or phenobarbital. The competitive binding assays are rapid and can detect cytochrome P-450 in less than 100 ng of microsomal protein. The RIA was used to examine the distribution of MAb-specific cytochromes P-450 in extrahepatic tissues of MC-treated rats; an approximately 30- to 50-fold greater amount of MC-P-450 in liver relative to lung and kidney was observed, which corresponds well with aryl hydrocarbon hydroxylase activity in these tissues. The inducibility of MAb-specific cytochromes P-450 in several species was also examined by competitive RIA. Significant increases in the MAb-specific P-450 were observed in MC-treated rats, guinea pigs, and C57BL/6 mice, all highly inducible for aryl hydrocarbon hydroxylase; little increase was observed for the relatively noninducible DBA/2 mouse strain.

Monoclonal antibody-directed immunopurification and identification of cytochromes P-450

Several rat liver cytochromes P-450 have been substantially purified in a one-step immunoadsorption procedure using Sepharose-bound monoclonal antibodies (MAbs) to the major forms of rat liver cytochrome P-450 induced by 3-methylcholanthrene and phenobarbital (MC-P-450 and PB-P-450, respectively). When mixed with solubilized rat liver microsomes the immunoadsorbent based on the MAb to MC-P-450 binds two polypeptides of MW 56,000 and 57,000 while the immunoadsorbent made with the MAb to PB-P-450 absorbs a species of MW 54,000. These polypeptides are readily desorbed by 0.1 M glycine (pH 3.0). Isolation of MAb-specific cytochrome P-450 isozymes by this method has applications in numerous phases of cytochrome P-450 research.

Inhibition of 2-acetylaminofluorene oxidations by monoclonal antibodies specific to 3-methylcholanthrene-induced rat liver cytochrome P450

The inhibitory effects of ten monoclonal antibodies specific for methylcholanthrene (MC)-induced P450 were determined on both C- and N-hydroxylations of 2-acetylaminofluorene (AAF) by liver microsomes from rats pretreated with MC, phenobarbital as well as untreated animals. The inhibitory effects of these antibodies were also determined on AAF hydroxylations by purified rat liver MC-P450. The inhibition patterns of AAF hydroxylations with both microsomes and the purified P450 indicate that the formation of 7-OH-, 5-OH-, 3-OH-, 1-OH- and N-OH-AAF was catalyzed by the same unique isoenzyme or at least isoenzymes of common antigenic determinants.

Identification and quantitation of a 2.0-kilobase messenger ribonucleic acid coding for 3-methylcholanthrene-induced cytochrome P-450 using cloned cytochrome P-450 complementary deoxyribonucleic acid

We have used a plasmid containing DNA complementary to one of the two size classes of mRNA coding for 3-methylcholanthrene-induced cytochrome P-450 from rat liver to characterize and quantitate that mRNA. The plasmid used was constructed and identified as follows: Total poly(A+) RNA from 3-methylcholanthrene-induced liver was used as a template for cDNA synthesis. Double-stranded cDNA was inserted into plasmid pBR322 by the G-C tailing procedure. Recombinants were screened by colony hybridization using as probe [32P]cDNA prepared from partially purified cytochrome P-450 mRNA. A differential screening approach was used in which duplicate filters were hybridized with probe from either 3-methylcholanthrene treated or untreated rats. Plasmid p23 was strongly positive by colony hybridization. It was conclusively shown to contain cytochrome P-450 cDNA sequences by demonstrating that the mRNA which specifically hybridized to nitrocellulose-bound plasmid p23 could be translated in vitro into peptides that were immunoprecipitable with monoclonal antibodies specific for 3-methylcholanthrene-induced cytochrome P-450. The size and quantity of the mRNA complementary to plasmid p23 were determined by hybridization of the 32P-labeled plasmid to rat liver RNA that had been fractionated by electrophoresis under fully denaturing conditions and transferred to diazobenzyl-oxymethyl-paper. Plasmid p23 hybridized strictly to a single size of mRNA that was about 2000 nucleotides in length, the smaller of the two size classes of mRNA coding for 3-methylcholanthrene-induced cytochrome P-450. From this we concluded that, at least within the region of the mRNA contained within the insert of plasmid p23, the two size classes of 3-methylcholanthrene-induced cytochrome P-450 mRNA were very different in sequence. The mRNA complementary to plasmid p23 was increased about 4-fold after in vivo administration of 3-methylcholanthrene under conditions that result in maximal induction of 3-methylcholanthrene-induced cytochrome P-450 enzymatic activity. This increase in cytochrome P-450 mRNA parallels the increase in cytochrome P-450 enzymatic activity observed after 3-methylcholanthrene administration. These data suggest that the regulation of mRNA levels is an important point of control of cytochrome P-450 gene expression.

Phenotyping of cytochromes P-450 in human tissues with monoclonal antibodies

Cytochrome P-450 (P-450)-dependent aryl hydrocarbon hydroxylase (AHHase) and 7-ethoxycoumarin deethylase (ECDEtase) in human tissues were differentially inhibited by monoclonal antibodies (MAbs) that were prepared to inhibit and completely inhibited the activity of 3-methylcholanthrene-induced rat liver P-450. The AHHase and ECDEtase of placentas from individual women who smoked were inhibited by the MAbs by 83-90% and by 34-74%, respectively. Benz[a]anthracene (BaA)-induced AHHase and ECDEtase in lymphocytes were inhibited 18-65% and 30-78%, respectively. The enzymes in both control and BaA-induced human cells in culture were inhibited to different extents. Both the AHHase and ECDEtase in control and BaA-induced monocytes and in normal liver were largely unaffected by the MAb. Thus, we have with the MAbs: (i) identified P-450s with a common antigenic site in placenta, lymphocytes, and human cells in culture; (ii) identified two forms of hydrocarbon-induced P-450s in lymphocytes, at least one of which is common with the induced P-450s of placenta and with a P-450 form present in uninduced lymphocytes; (iii) identified two forms of P-450 responsible for smoking-induced ECDEtase activity in placenta, one of which is also responsible for AHHase activity; (iv) shown that the P-450s of liver, basal, and BaA-induced monocytes are different from the MAb-sensitive P-450s of placenta and lymphocytes; (v) quantitated in several human tissues the percentages of control and inducible AHHase and ECDEtase that are dependent on the MAb-sensitive P-450; and (vi) defined by HPLC the contribution of the MAb-sensitive P-450 to the formation of specific benzo[a]-pyrene metabolites. The results demonstrate the value of MAbs for defining antigenic site relatedness for different enzymatic functions of P-450s and for identifying and quantifying the amount of a specific enzyme activity in a tissue dependent on specific P-450s. This study may be a prototype for the use of MAbs for phenotyping and mapping of P-450s responsible for specific metabolic reactions and, thus, may be useful in determining the relationship of P-450 phenotype to individual differences in drug metabolism and carcinogen susceptibility.

Monoclonal antibodies to rabbit liver cytochrome P-450LM2 and cytochrome P-450LM4

Monoclonal antibodies were prepared from hybridoma clones isolated by the fusion of myeloma cells and spleen cells derived from mice immunized with either purified rabbit liver microsomal cytochrome P-450LM2 or cytochrome P-450LM4. Seven hybridoma clones produced three kinds of monoclonal antibodies to P-450LM2. The first class bound, precipitated, and inhibited the enzyme activity of P-450LM2 for both benzo[a]pyrene hydroxylation and 7-ethoxycoumarin deethylation. The other two classes either bound and precipitated or only bound the enzyme. These monoclonal antibodies to P-450LM2 showed a precipitin reaction and inhibition of enzyme activity that was specific for cytochrome P-450LM2. Thus, they did not react with or inhibit the enzyme activity of the other isozyme cytochrome P-450LM4, Fraction 1 or Fraction 7. All of the monoclonal antibodies formed against P-450LM2 were mouse immunoglobulin (Ig) subclass IgG1. The most effective monoclonal antibody strongly inhibited the formation of oxygenated metabolites of benzo[a]pyrene at various positions as well as the deethylation of 7-ethoxycoumarin. Four hybridomas were isolated which produced monoclonal antibodies to P-450LM4. One of the four was of the IgM class and three were of the IgG1 type. The four monoclonal antibodies bound to P-450LM4 but did not precipitate the enzyme, and did not bind to P-450LM2. The monoclonal antibody P-450LM4 complexes interacted with protein A, and the enzyme activity for benzo[a]pyrene hydroxylation could be removed by centrifugation. The high specificity and monoclonality of these antibodies suggest their potential usefulness for studying the genetics, regulation, and roles of the different isozymes of P-450LM in drug and carcinogen metabolism.

Effect of halothane, enflurane, and nitrous oxide on tracheal ciliary activity in vitro

Effects of halothane, enflurane, and nitrous oxide on ciliary beats were evaluated using a photoelectric system in dissected rabbit tracheal segments. Dose-dependent suppression of the frequency of ciliary beats of moderate degrees was observed after exposure of tracheal segments to warmed and humidified vapors of halothane and enflurane. No suppression, however, was noted after exposure to nitrous oxide. These findings suggest that halothane and enflurane directly suppress ciliary activity.

Isolation and characterization of glycoproteins from canine tracheal pouch secretions

Canine tracheal pouch secretions were solubilized with 1% sodium dodecyl sulfate and visualized by sodium dodecyl sulfate-agarose-acrylamide gel electrophoresis. Intact mucus, and water-soluble and insoluble fractions of mucus were shown to be composed of high molecular weight glycoproteins (Mr greater than or equal to 3 . 10(6)) and three major classes of proteins of lower molecular weight (Mr approximately 4 . 10(5), 2 . 10(5), and 6 . 10(4)). When the mucus secretions were further treated with a reducing agent, the glycoproteins were dissociated into subunits which appeared on the gel as three discrete bands. Separation of the high molecular weight glycoproteins from the other proteins was achieved by gel filtration on Biogel A-15m in the presence of 1% dodecyl sulfate following reduction and alkylation of mucus. These glycoproteins were further resolved, using DEAE cellulose chromatography in the presence of 6 M urea, into two protein fractions. Both fractions contained approximately 87% carbohydrate, high amounts of serine and threonine but differed significantly in contents of N-acetyl glucosamine and sialic acid; their mobility on gel electrophoresis was also different. Significant contents of cysteine were noted in both fractions. Results of this study indicate that the canine tracheal pouch preparations provide normal tracheal secretions which bear similarity in structure to the tracheobronchial secretions obtained from human patients.

Staphylococcal Enterotoxin A and C Production with Various Sugars as Energy Source 1

One percent added sugar (sucrose, maltose, lactose, glucose and glucose plus fructose) to casein hydrolysate (NAK) medium with or without starch or low methoxyl pectin did not significantly affect enterotoxin C production but did significantly decrease the pH at 12 and 24 h. The increased viscosity of colloidally thickened media resulted in decreased aeration in shaken cultures and decreased quantities of enterotoxin C. Sugars tested did not differ practically in their effects on the parameters of multiplying Staphylococcus aureus 361 and 265-1 which were measured. Addition of 1% of glucose, sucrose, or maltose prevented the decreased growth rate observed when strain 265-1 was grown in 20% O₂ + 80% N₂ instead of air.

An animal model of cigarette smoking in beagle dogs: correlative evaluation of effects on pulmonary function, defense, and morphology

Using beagle dogs, we have developed an animal model for the evaluation of the effect of chronic cigarette smoking on pulmonary defense and function and on lung structure. The smoking apparatus developed allows the dog actively to inhale properly diluted (1:4) smoke directly from the cigarette through a mouthpipe. In this model, 6-month and 1-year periods of mild to moderate smoking caused impairment of tracheal mucociliary transport and bacteriosuppressive activity of alveolar macrophages, with little change in pulmonary function. Morphologically, subtle, but significant, lesions were noted in the central airways and bronchiolar walls, consisting of tracheal epithelial basal cell hyperplasia, proliferation of goblet cells in central airways, and peribronchiolar infiltration by inflammatory cells. Morphometry of bronchiolar size distribution, volume proportion of parenchymal structure, and alveolar surface area, however, failed to show significant differences between the groups.

Hydrogenase and ribulose diphosphate carboxylase during autotrophic, heterotrophic, and mixotrophic growth of scotochromogenic mycobacteria

Two key autotrophic enzyme systems, hydrogenase and ribulose diphosphate carboxylase, were examined in Mycobacterium gordonae and two other chemolithotrophic, scotochromogenic mycobacteria under different cultural conditions. In all three organisms both enzymes were inducible and were produced in significant levels only in the presence of the specific substrate, hydrogen or carbon dioxide. M. gordonae exhibited increased growth rates and yields, indicating mixotrophic growth, in the presence of a number of single organic substrates, including acetate, pyruvate, glucose, fructose, and glycerol. In contrast to other aerobic hydrogen autotrophs, the presence of either acetate or pyruvate did not repress ribulose diphosphate carboxylase, and mixotrophic growth was rapid with these substrates. In the absence of carbon dioxide, growth in glycerol medium under an atmosphere of hydrogen and oxygen was severely inhibited, even with cells preadapted to heterotrophic growth on glycerol. Cyclic adenosine monophosphate was not effective in inducing hydrogenase or carboxylase in heterotrophic, mixotrophic, or hydrogen-inhibited cultures.

Severe pleural restriction: the maximum static pulmonary recoil pressure as an acid in diagnosis

Three patients with pleural restriction are presented in detail. One patient had had a right pneumonectomy and died of ventilatory failure due to left-sided restrictive pleurisy. The second patient had neoplastic pleural effusion and inactive tuberculosis. The third patient had systemic lupus erythematosus with bilateral restrictive pleuritis. The physiologic picture was similar in the three cases, with marked decrease of lung volumes, increase of the RV/TLC ratio, absence of airways obstruction, decrease of the Dco and decrease of dynamic lung compliance. In addition, each of these three patients and others with severe pleural restriction had a lower than normal maximum static pulmonary recoil pressure (Pmax). Since in pulmonary restrictive disease, the Pmax was found to be elevated, it was a useful test for distinguishing pulmonary restriction from pleural restriction.

D-Fucose as a gratuitous inducer of the L-arabinose operon in strains of Escherichia coli B-r mutant in gene araC

d-Fucose, a nonmetabolizable analogue of l-arabinose, prevents growth of Escherichia coli B/r on a mineral salts medium plus l-arabinose by inhibiting induction of the l-arabinose operon. Mutations giving rise to d-fucose resistance map in gene araC and result in constitutive expression of the l-arabinose operon. Most of these mutations also permit d-fucose to serve as a gratuitous inducer. It is concluded that d-fucose-resistant mutants produce an araC gene product with an altered inducer specificity. Addition of l-arabinose to cells induced with the gratuitous inducer, d-fucose, resulted in severe transient repression of operon expression followed by permanent catabolite repression. Transient repression but no permanent catabolite repression was obtained when cells unable to metabolize l-arabinose were employed. It is concluded that transport of l-arabinose alone is sufficient to achieve transient repression of its own operon, but that metabolism of l-arabinose must occur to achieve permanent catabolite repression of the l-arabinose operon. This general effect has been termed "self-catabolite repression."